Process for the manufacture of new metallizable 4-hydroxy-5-carboxyphenyl-2:2&#39;-dihydroxy-azo-dyestuffs



3,060,167 PROCESS FGR THE MANUFACTURE OF NEW R/ETALLIZABLE 4 HYDROXY 5CARBGXY- PHENYL-Z:2-DlHYDROXY-AZ9-DYESTUFFS Franz Graf, Basel,Switzerland, assignor to Durand & Huguenin A.G., Basel, Switzerland, 2Swiss Company No Drawing. Filed Jan. 15, 1959, Ser. No. 786,930 Claimspriority, application Switzerland Jan. 17, 1958 8 Claims. (Cl. 260-173)This invention provides a process for the manufacture of newmetallizable 4-hydroxy-5-carboxyphenyl-Z:2'-dihydroxy-azo-dyestuffs,which contain at least one atomic grouping of the formula HOOG in whichR represents the residue of a coupling component in which the hydroxylgroup is in a position vicinal to the carbon atom capable of coupling.

The aforesaid dyestuffs are obtained by a first process for themanufacture of 4-hydroxy-5-carboxyphenyl-Z:2'- dihydroxy-azo-dyestuffsin which a 1-amino-2-arylsu1- phonyloxy-4-hydroxybenZene-S-carboXylicacid is diazotized and the diazo-cornpound so obtained is coupled with acoupling component which contains a hydroxyl group in a position vicinalto the carbon atom capable of coupling. From the resulting arylsulphonylester of the 4- hydroxy-S-carboxyphenyl-2 2'-dihydroxy-azo-dyestufi thearylsulphonyl residue is then split off by hydrolysis in an alkalinemedium. The dyestuffs so obtained, which contain at least one atomicgrouping of the Formula I above, can be converted into complex metalcompounds, and are especially useful for chrome printing on cotton. Thedyeings and prints are distinguished by their very good fastness tolight and properties of wet fastness.

However, the above process has various disadvantages, especially thetendency for the arylsulphonyl residue to split off during themanufacture of the arylsulphonyl ester dyestutf in an alkaline medium.

Furthermore, dyestuffs which contain no sulphonic acid groups aregenerally so sparingly soluble in water that they cannot be used fordyeing or printing by the usual methods.

A further disadvantage of the aforesaid arylsulphonyl ester dyestuffs isthat it is practically impossible to metallize them on the fibre,because the alkaline hydrolysis of the arylsulphonyl ester when fixedwith chromium on the fibre proceeds too slowly and damage may thereby becaused to the fibre.

The present invention provides a process for the manufacture, in asimple manner and in very good yield, of metallizable 4hydroxy-S-carboxyphenyl-Z:2-dihydroxyazo-dyestuffs which contain atleast one atomic grouping of the formula 3,060,167 Patented Oct. 23,1962 is diazotized, the resulting diazo-compound is coupled with acoupling component which contains a hydroxyl group in ortho-position tothe carbon atom capable of coupling, and the resulting4-hydroxy-5-carboxyphenyl- 2-monosulphuric acidester-2'-hydroxy-azo-dyestuff, which contains at least one atomicgrouping of the formula 11 0- N=N I lno oh no (a) Sulphuric acidmono-(S-hydroxy-4-carboxyphenyl) ester Dry 2:4-dihydroxybenzoic acid isintroduced with the exclusion of moisture into a mixture of pyridine andchlorosulphonic acid. The esterification is completed in the course of5-6 hours at a moderately raised temperature, advantageously 5070 C. Thereaction mixture is poured on to an excess of sodium carbonate, Water iscautiously added, and the pyridine is expelled by introducing steam.There is obtined a clear alkaline solution of the sulphuric acidmono-(3-hydroxy-4-carboxyphenyl) ester.

(b) Sulphuric Acid M0n0-[5-Hydr0xy-4-Carb0xy-2-(4'-Chloraphenylazo)-Phenyl-(1 Ester 4-ohloraniline is diazotized in theusual manner, and coupled in the presence of an excess of sodiumcarbonate with the sulphuric acid mono-(3-hydroxy-4-carboxyphenyl) esterobtained as described under (a) above. Towards the end of the couplingreaction the mixture is heated to 50- 60 (3., whereupon the partiallyprecipitated ester dyestuif dissolves. The mixture is filtered to removeimpurities and the ester dyestuif is precipitated by the addition ofsodium chloride.

The dried disodium salt of the yellow ester dyestufi has the followinganalytical data (calculated as the anhydrous and salt-free product).

C H O N ClSNa Calculated, N, 6.73%; CI, 8.53%; S, 7.69%; (11101 416.5).Found: N, 6.76%; Cl, 8.47%; S, 7.76%.

3 (c) Sulphuric Acid Mono-(5-Hydr0xy-4-Carb0xy-2- Aminophenyl) Ester Theester dyestuff obtained as described under (b) above is treated, forexample, in the presence of an excess of caustic soda solution withsodium hydrosulphite at a temperature of 7595 C. The solution, which isdecolorized by the reduction, is freed from 4-chloraniline by steamdistillation and then cooled to C. The decomposition products of thesodium hydrosulphite which crystallize out are removed, and hydrochloricacid is added to the clear solution at a temperature of about C.,whereby the sulphuric acid mono-(S-hydroxy-4'carboxy-2-aminophenyl)ester precipitates as the internal salt. The precipimic is filtered off,washed neutral and dried, whereby there is obtained in excellent yield apale grey powder which has the following analytical data (calculated asthe anhydrous and salt-free product).

C H O NS (249): Calculated, N, 5.63%; S, 12.85%. Found: N, 5.59%; S,12.86%.

In the process of the invention the diazotization of the sulphuric acidmono-(5-hydroxy-4-carboxy-Z-aminophenyl) ester is advantageously carriedout at a temperature below 0 C., in order to prevent prematurehydrolysis of the sulphuric acid ester and any nitrozation. Preferablythe so-cal1ed indirect method of diazotization is used by allowing asolution of the disodium salt of the sulphuric acidmono-(5-hydroXy-4-carboxy-2-aminophenyl) ester and sodium nitrite to runinto a mixture of ice, sodium chloride and hydrochloric acid in suchmanner that the temperature does not rise above 5 C. The diazocompoundprecipitates in the form of the internal salt and may be filtered offand washed neutral with ice water. The diazo-compound so obtained isstable in a neutral or alkaline medium.

The coupling of the diazotized sulphuric acid mono-(5-hydroxy-4-carboxy-2-aminophenyl) ester with the coupling componentscontaining in a position vicinal to the carbon atom capable of couplinga hydroxyl group or an enolizable keto group, may be carried out by theusual methods in the presence of an alkali. If desired, the couplingreaction may be accelerated by the addition of a small proportion ofpyridine or by heating.

As coupling components there may be used the customary azo-dyestutfcoupling components which contain in a position vicinal to the carbonatom capable of coupling a hydroxyl group or an enolizable keto group.

(A) Among coupling components that yield monoazodyestufis there may bementioned, for example 1:3-dihydroxybenzene, 2:4-dihydroxybenzoic acid,acetoacetylaminobenzene, 4-acetoacetylamino-l-chlorobenzene,3-acetoacetylaminobenzene-sulphonic acid,5-acetoacetylamino-2-hydroxybenzoic acid,1-(3carboxy-4-hydroxyphenyl)-3-met'hyl-5-pyrazolone,Z-hydroxynaphthalene, 2-hydroxynaphthalene-3:6-disulphonic acid,1hydroxy-8-aminonaphthalene-3-sulphonic acid,1=hydroxy-8-aminonaphthalene-3:6 and -4:5-disulphonic acid and acylationproducts thereof.

(B) If desired, 2 molecular proportions of the diazotized sulphuric acidmono(5 hydroxytcarboxy-Z-aminophenyl) ester may be coupled with 1molecular proportion of a component capable of coupling twice, whichcontains in a position vicinal to each carbon atom capable of coupling ahydroxyl-group or a group convertible into an enolizable group. Asexamples of such components there may be mentioned:

1:3-dihydroxybenzene,

l:S-dihydroxynaphthalene-S:6-disulphonic acid,

1 hydroxy-8-acetoa-cetylaminonaphthalene-3:6-disulphonic acid,

5:5-dihydroxynaphthyl-(2:2)-amine disulphonic acid- (C) As couplingcomponents which contain in a position vicinal to the carbon atomcapable of coupling a hydroxyl group or a group convertible into anenolizable group, and also contain an azo-linkage, there are to beunderstood azo-dyestuffs obtainable by diazotizing an aromatic aminooraminoazo-compound, and coupling the diazo compound in an acid mediumwith an aminonaphthol sulphonic acid, for example, the product obtainedby coupling diazotized 4-nitraniline in an acid medium withl-amino-8-naphthol-3:6-disulphonic acid, or products obtained bycoupling with one molecular proportion of a component capable ofcoupling twice such, for example, as4:2-dihydroxy-l:l-azobenzene-4-sulphonic acid.

The new sulphuric acid monoesters of4-hydroxy-5-carboxyphenyl-Z:2-dihydroxy-azo-dyestulfs which contain atleast one atomic grouping of Formula III can be isolated by knownmethods and, if desired, purified.

The new dyestufis that contain at least one atomic grouping of theFormula III contain in one and the same molecule a group capable offorming complexes and also a system convertible into a group capable offorming complexes, since the atomic grouping of the Formula III can beconverted by treatment with an acid into an atomic grouping of theFormula I accompanied by the splitting of the sulphuric acid ester(ester splitting).

The dyestutfs can be used for dyeing in any one of the following wayswith ester splitting on the fibre:

(a) Dyeing, ester splitting on the fibre, and metallization,

(b) Dyeing, metallization, ester splitting on the fibre and furthermetallization, or

(c) Metallization, dyeing, ester splitting on the fibre and furthermetallization,

or with ester splitting in substance:

(03) Ester splitting in substance, dyeing and metallization,

(e) Ester splitting in substance, metallization, dyeing and furthermetallization.

Depending on their constitution, the dyestufis containing at least oneatomic grouping of the Formula III produce various tints on animal,vegetable and synthetic fibres, and some of them are also suitable fordyeing anodically oxidized aluminium. In general, the dyeings are strongand .brilliant, but have only moderately good fastness properties. Inchrome printing, in after-chroming on the fibre and in dyeingpre-chromed fibres, while retaining the ester grouping in the FormulaIII, much better properties of wet fastness and in some cases also abetter fastness to light than has hitherto been possible are obtainedowing to complex formation at the ortho-hydroxycar-boxyphenyl group.

The same result is obtained by subjecting the ester dyestufifs to ashort treatment at a moderately raised temperature with an agentyielding chromium, such as chromium acetate, whereby the chromium entersthe ortho-hydroxycarboxyphenyl group and the ester grouping in the-Formula III. Complexes of this type are distinguished by their verygood solubility and good capacity for being fixed.

By treating with an acid a dyestuff that contains at least one atomicgrouping of the Formula III, the sulphuric acid ester is split and adyestuif is formed that contains at least one atomic grouping of theFormula I. With a strong acid, such as hydrochloric acid or sulphuricacid, the ester is split even at room temperature, whereas with a weakacid, such as acetic acid, a higher temperature is required to bringabout ester splitting at an appreciable speed.

When the ester splitting is carried out on the fibre, it is of advantageto subject to such splitting a dyeing that has been fixed with chromium,in order to prevent bleeding of the dyestufi'. Subsequent treatment withan agent yielding metal produces dyeings distinguished by their verygood properties of wet fastness and fastness to light.

When the ester splitting is carried out in substance, 4- hydroxy 5carboxyphenyl 2:2'-dihydroxy-azo-dyestuifs are formed that contain atleast one atomic grouping of the Formula I. Dyeings produced with thesedyestuffs can be after-treated by the usual methods with agents yieldingmetal, more especially with compounds of copper and chromium, wherebythe general properties of fastness are considerably improved.

Alternatively, the dyestuffs that contain at least one atomic groupingof the Formula I may be converted into metal complexes by treating themin substance by known methods with an agent yielding metal. Themetalliferous dyestuifs so obtained, when they contain sulphonic acidgroups, are suitable for dyeing animal, vegetable and synthetic fibres,and also for dyeing anodically oxidized aluminium. Dyeings produced withdyestuffs, which contain metal bound in complex union with theortho-dihydroxyaZ-o-group and in which the ortho-hydroxy-carboxyphenylgroup as yet contains no heavy metal in complex union, can beafter-treated with an agent yielding a metal, preferably with a chromiumcompound, whereby the properties of wet fastness are considerablyimproved. The metalliferous dyestuffs containing sulphonic acid groupsare especially useful in chrome printing. In printing on cotton theyreduce tints having very good properties of wet fastness and fastness tolight, and some of them are remarkably pure.

An especially advantageous form of the process consists in subjecting adyestutf that contains at least one atomic grouping of the Formula 11-1in substance or preferably on the fibre to ester splitting andmetallization in the same operation. This is achieved by treating thedyestuff in a neutral to weakly acid medium at a temperature of 40 C. to95 C. with an agent yielding metal. The agent yielding metal may be asimple metal salt, such as a sulphate, chloride or acetate, or acompound in which the metal is bound in complex union, such as anaromatic or aliphatic hydroxy-carboxylic acid, dicarboxylic acid oramino-carboxylic acid. Especially good results are obtained by fixing onthe fibre with chromium a dyestuff that contains at least one atomicgrouping of the Formula HI, and after-treating the dyeing in a neutralto weakly acid medium at a raised temperature with a copper salt.

As compared with the above-described first process, the process of thisinvention has, inter alia, the following advantages:

The sulphuric acid mono-(5-hydroxy-4-carb0xy-2- aminophenyl) ester andthe ester dyestufis made therefrom are stable in an alkaline medium evenat raised temperatures. The stability of alkalies considerablyfacilitates the manufacture of the dyestuffs and leads in some casesalso to better tinctorial yields.

Further advantages of the process of this invention are the goodsolubility of the ester dyestufis formed as intermediates and the factthat they are easy to metallize on the fibre.

By coupling sulphuric acid mono-(5-hydroxy-4-car boxy-Z-aminophenyl)ester with a component that is free from sulphonic acid groups, such as1:3-dihydr0xybenzene, a dyestuff is obtained that is readily soluble inwater and can be fixed on the fibre in chrome printing withoutdifiiculty. By after-treating the dyeing for a few minutes with coppersulphate or other copper salt, the sulphuric acid ester is split and theortho-ortho-dihydroxyazocopper complex is also formed, and prints areobtained 6 that are fast to washing and possess an excellent fastness tolight.

The following examples illustrate the invention, the parts being byweight unless otherwise stated, and the relationship of parts by weightto parts by volume being the same as that of the kilogram to the litre:

EXAMPLE 1 24.9 parts of sulphuric acid mono-(5-hyd'roxy-4-carboxy-Z-aminophenyl) ester (molecular weight: 249) are dissolved in 100parts of cold water with 20 parts by volume of aqueous sodium hydroxidesolution of 30% strength, and the solution is mixed with 25 parts byvolume of a 4 N-solution of sodium nitrite. The clear solution is slowlystirred into a mixture of 400 parts of ice, 100 parts by volume ofsaturated sodium chloride solution and 60 parts by Volume ofhydrochloric acid of 30% strength in a manner such that the temperaturedoes not rise above 5 C. The diazotization is complete after 10-2Ominutes. The precipitated diazo-compound is isolated, and introducedinto a previously prepared solution in 200 parts of water of 60' partsby volume of aqueous sodium hydroxide solution of 30% strength, 10 partsof pyridine, 100 parts of ice and 35 parts of the disodium salt of2-hydroxy-naphthalene-3:6-disulphonic acid (molecular weight: 348). Themixture is stirred until the coupling is complete, the coupling solutionis adjusted to a pH value of 9 with acetic acid, and the whole is heatedto 4050 C. The dyestuff is precipitated with 300 parts of sodiumchloride, filtered off and dried in vacuo at 6080 C.

In the form of its free acid the ester dyestuff obtained in this mannercorresponds to the structural formula (l)SOaH HO SOaH Hoot S OsH andforms a reddish brown powder which dissolves in water and concentratedsulphuric acid with red coloration. In chrome printing on cotton ityields a bluish violet dyeing; when after-treated with copperacetate-l-acetic acid at C., accompanied "by cleavage of the sulphuricacid ester and simultaneous formation of theortho-ortho-di-hydroxyazo-copper complex, a redviolet tint is obtainedwhich is fast to washing and possesses excellent fastness to light.

The identical result is achieved by after-treatment with copper sulphateat 60-70" C.

EXAMPLE 2 50 parts of the ester dyestufi prepared as described inExample 1 are dissolved in 750 parts of water at room temperature andmixed with 60 parts by volume of hydrochloric acid of 30% strength. Aclear red-orange solution is obtained which gives a distinct mineralacid reaction. It is left to itself for 48 hours at room temperatureafter which the splitting of the sulphuric acid ester is complete, and75 parts of calcined sodium carbonate are then cautiously added. Thesolution, which now has an intensely blue-violet coloration, is heatedto 4050 C., and the dyestuff is precipitated with sodi-um chloride. Theisolated and dried dyestuif corresponds in the form of its free acid tothe structural formula OH HO SOsH SOaH and forms a violetish brownpowder; its solution in water is reddish blue and in concentratedsulphuric acid bluish red. :In chrome printing on cotton it produces aviolent tint which on after-treatment with copper acetate --accompaniedby formation of the ortho-ortho-dihydroxyazo-copper complex-produces areddish violet tint which is very fast to light, on wool a violet tint,and on anodically oxidized aluminium a bluish red.

EXAMPLE 3 50 parts of the ortho-ortho-dihydroxyazo dyestufr obtained asdescribed in Example 2 are dissolved in 500 parts of water at 9095 C..100 parts of a chromium acetate solution containing 5.5 parts ofchromium are stirred in dropwise. The whole is stirred to complete theformation of the ortho-ortho'-dihydroxyazo-chromium complex, and thevery readily metallizable dyestulf is isolated by evaporating thereaction mixture to dryness in vacuo.

The resulting chromiferous monoazo dyestuif forms a dark violetishpowder which dissolves in water and in concentrated sulphuric acid withviolet coloration. In chrome printing on cotton it gives a fastblue-violet tint.

When the chromium solution is replaced by an equiv alent amount ofcobalt solution, a grey violet tint is obtained in chrome printingcotton.

When the chromium solution is replaced by an equivalent amount of copperacetate or copper tetramine, a dyestuif is formed which produces oncotton in chrome printing a pure red violet of very good fastness tolight.

EXAMPLE 4 When in Example 1, 2-hydroxynaphthalene-3:6-disulphonic acidis replaced by an equivalent amount of 1- hydroxynaphthalene-4-sulphonicacid, a sulphuric acid monoester dyestutf of similar properties results.

When the sulphuric acid ester is split as described in Example 2, thecorresponding ortho-ortho'-dihydroxyazo dyestufi is formed; it ismetallized as described in Example 3, to yield the followingmetalliferous azo dyestuffs.

Metal bound in complex union to Tint produced in chrome theorthomrthodihydroxyazo printing on cot-ton group:

Chromium Red-violet. Cobalt Claret.

Copper Claret.

The dyeings are distinguished by good fastness to light and washing.

EXAMPLE 5 24.9 parts of sulphuric acidmono-(5-hydroXy-4-carboxy-Z-aminophenyl) ester (molecular Weight: 249)are diazotized as described in Example 1. The diazo suspension is addedto a prepared solution consisting of 16 parts of 2:4-dihydroxybenzoicacid (molecular weight 154), 100 parts by volume of aqueous sodiumhydroxide solution of 30% strength, 20 parts of pyridine, 50 parts ofwater and 50 parts of ice. The whole is stirred at room temperature tocomplete the coupling; the coupling solution is then adjusted to pH=8.5with 25 parts of acetic acid of 80% strength and heated to 40-50 C. Thedyestuif is salted out with 300 parts of sodium chloride, filtered offand dried in vacuo at 60-80" C.

In the form of its free acid the readily soluble dyestutf corresponds tothe structural formula (l)SOsH OH and forms a dark brown powder whichdissolves in water with yellow-brown coloration and in concentrated sul-Q o ph-uric acid with brown coloration. In chrome printing on cotton itproduces a deep brown tint. On after-treatment with copper sulphate for5-10 minutes at fill-70 C.which is accompanied by cleavage of thesulphuric acid ester and by simultaneous formation of the ortho:ortho'-dihydroxyazo-copper complex--a violetish brown tint results whichhas excellent fastness properties to washing and light.

An identical result is obtained by after-treating with copper acetatefor 5-10 minutes in an acetic acid solution at -95 C.

EXAMPLE 6 24.9 parts of sulphuric acidmono-(5-hydroxy-4-carboxy-Z-aminophenyl) ester (molecular weight 249)are diazotized as described in Example 1. The diazo suspension is addedto a solution consisting of 11 parts of l:3-dihydroxybenzene (molecularweight 20 parts of pyridine, 85 parts by volume of aqueous sodiumhydroxide solution of 30% strength and 100 parts of water. On completionof the coupling the dyestuff is precipitated with sodium chloride atpH=8.5, isolated and dried. A reddish brown powder is obtained whichdissolves in Water with yellow coloration and in concentrated sulphuricacid with yellow-brown coloration. In chrome printing on cotton itproduces a strong reddish brown tint which, on after-treatment withcopper sul phateaccompanied by splitting of the sulphuric acid ester andby simultaneous formation of the orthozortho dihydroxyazo-coppercomplex-produces a deep brown tint which is fast to washing and hasexcellent fastness to light.

EXAMPLE 7 24.9 parts of sulphuric acidmono-(5-hydroxy-4-carboxy-Z-aminophenyl) ester (molecular weight 249)are diazotized as described in Example 1. The diazo suspension is addedto a solution consisting of 18 parts of acetoacetylaminobenzene(molecular weight 177), 200 parts of water, 50 parts of pyridine andparts of calcined sodium carbonate. Towards the end of the couplingreaction the whole is raised to 4050 C., and the dye-stuff isprecipitated by adding 180 parts of sodium chloride. After isolating anddrying it, a yellow powder is obtained which dissolves in water and inconcentrated sulphuric acid with yellow coloration. In chrome printingon cotton it produces a brilliant yellow tint of good fastness towashing which, on being after-coppered with copper sulphate-accompaniedby cleavage of the sulphuric acid ester and by simultaneous formation ofthe orthozortho dihydroxyazo copper complex-yields a brownish yellowtint of very good fastne-ss to light.

Dyestuffs having similar properties result when 1- chloro 4acetoacetylaminobenzene or 3 acetoacetylaminobenzene-l-sulphonic acid isused as coupling component.

EXAMPLE 8 When the coupling is performed according to Example 7 with 24parts of S-acetoacetylamino-Z-hydroxybenzoic acid (molecular weight237), a yellow-brown powder is obtained which dissolves in water and inconcentrated sulphuric acid with yellow coloration. In the form of itsfree acid the dyestuif corresponds to the following structural formulaCOOH N=NC CONH- OH HO 49.7 parts of this dyestufi (molecular weight 497)are dissolved in 500 parts of water. The clear yellow solution is mixedwith 100 parts of a chromium acetate solution containing 15 parts ofchromium, and the mixture is heated for minutes at 80-85 C. Withoutcleavage of the sulphuric acid ester, the very readily solubledichromium complex of the dyestufi is obtained in which chromium isbound to the two ortho-hydroxy-carboxy groups.

This dark-brown dyestufi solution dyes natural silk, Wool, nylon, cottonand anodically oxidized aluminium clear, reddish yellow tints.

After-treatment of the above dyeings with copper sulphate at 60-70C.-accompanied by cleavage of the sulphuric acid ester and bysimultaneous formation of the orthozortho dihydroxyazo coppercomplex-produces yellow-brown tints, some of which have very goodfastness to light.

EXAMPLE 9 24.9 parts of sulphuric acidmono-(5-hydroxy-4-carboxy-2-aminophenyl) ester (molecular weight 249)are diazotized as described in Example 1 and coupled with 23.5 parts ofl-(4'-hydroxy-3-carboxyphenyl)-3-methyl- 5-pyrazolone (molecular weight234). After isolation and drying, the dyestufi is obtained in the formof an orange-coloured powder which dissolves in water with orangecoloration and in concentrated sulphuric acid with red-orangecoloration.

In chrome printing on cotton it produces a clear orange tint which isfast to washing and has good fastness to light; whenafter-copperedaccompanied by splitting of the sulphuric acid and bysimultaneous formation of the ortho:ortho'-dihydroxyazo-copper complexityields a brownish orange tint of outstanding fastness to light.

Further valuable metalliferous monoazo dyestuffs can be preparedaccording to Examples 1 to 8, some of which are shown in the followingtable:

Tint of copper'ed Example N 0. Component dyeing in chrome printing oncotton Z-hydroxy-naphthalene claret. 11 1 amino -8-hydroxynaphthalene-G- violet.

sulphonic acid. 12 1 amino 8 hydroxynaphthalene blue-violet.

izfi-disulphonic acid. 13 1 acetylamino -8- hydroxynaphtha- Do.lene-3zfi-disulphom'c acid. 14 1 benzoylamino 8 hydroxynaph- D0.

thalene-336-disulphonic acid. 15 1 (4- hydroxy -3 carboxybenzeneviolet.

sulphonylamino) 8 hydroxynaphthalene-3: fi disulphonic acid. 16 4 (2-hydroxynaphthalene 6- sulclaret.

phonyloxy) 2 hydroxybenzenel-carboxylic acid. 17 2 hydroxynaphthoie acid(3) Do.

am'lide.

EXAMPLE 18 24.9 parts of sulphuric acidmono-(5-hydroxy-4-carboxy-Z-aminophenyl) ester (molecular weight 249)are diazotized as described in Example 1. The diazo suspension is addedto a solution consisting of 5.5 parts of 1:3-dihydroxybenzene (molecularweight 110), 72 parts by volume of aqueous sodium hydroxide solution ofstrength, 20 parts of pyridine and 150 parts of ice water. The mixtureis stirred at room temperature to complete the coupling, the dyestuffsolution is adjusted to pH=8.5 by adding acetic acid, heated to 4050 C.,and the dyestufi is precipitated with sodium chloride. The dyestuffcorresponds in the form of its free acid to the structural formulaO-SOaH 00 OH It is filtered oif and dried in vacuo at 60 to 70 C. The

10 readily soluble dyestuflf forms a greyish black powder whichdissolves in water with brown coloration and in concentrated sulphuricacid with brownish violet coloration.

In chrome printing this dyestuif produces on cotton a dark brown tint.When after-coppered with copper sulphate at 50-70 C., or with copperacetate at 100 C.accompanied by splitting of the sulphuric acid esterand by simultaneous formation of the ortho:ortho-dihydroxyazo-coppercomplexes which can also be defined as thedi-ortho:ortho'-dihydroxyazo-copper complex compounda deep black tint isobtained which has excellent fastness to light and washing.

When this dyestuff is used for dyeing anodically oxidizer aluminum andthe dyeing is after-treated with aqueous copper sulphate solution (metalsealing) a brownish black of excellent fastness to light is obtained,accompanied by splitting of the sulphuric acid ester and simultaneousformation of the ortho:ortho'-dihydroxyazocopper complexes.

When the dyeings obtained on pre-chromed silk, wool and viscose rayonare after-copperedaccompanied by splitting of the sulphuric acid esterand by simultaneous formation of the ortho:ortho'-dihydroxyaZo-coppercomplexes-grey to black dyeings are obtained which are fast to washing,and some of them are also very fast to light. When pre-chromed nylon isdyed in the same manner, a brown dyeing results which is shifted toblack when subjected to an alkaline treatment in an aqueous medium at anelevated temperature (alkaline washing). The dyeing is distinguished byvery good fastness to wetting and light.

When 12.6 parts of the ester dyestufi (molecular weight 630) prepared asdescribed in the first paragraph of this example are dissolved at 6080C. in 400 parts of aqueous chromium acetate solution containing 3.5parts of chromium and the solution is stirred for some time, the readilysoluble ortho-hydroxy-carboxy dichromium complex of the ester dyestuifis obtained without splitting of the sulphuric acid ester. Thisdichromium complex can be isolated in the form of a brown violet powderby evaporation in vacuo at 40-50 C.

The aqueous solution of the ortho-hydroxy-carb'oxy dichromium complexcan be used as it is for dyeing silk, wool, viscose rayon, nylon andanodically oxidized aluminium. After-coppering produces the same tintsas mentioned above.

Further valuable disazo dyestuffs can be made in a similar manner, thusfor example:

EXAMPLE 22 46.8 parts of the monoazo dyestuif, obtained in the knownmanner from diazotized 4-nitro-1-aminobenzene (molecular weight 468) bycoupling with 1-amino-8- hydroxynaphthalene-3:6-disulphonic acid in anacid medium, are dissolved in 500 parts of water, 50 parts of pyridineand 60 parts by volume of aqueous sodium hydroxide solution of 30%strength. The solution is treated with 24.9 parts of the sulphuric acidmono-(S- hydroxy 4 carboxy 2 aminophenyl) ester (molecular weight 249)diazotized as described in Example 1, and the whole is stirred tocomplete the coupling. The dyestuif is then isolated in the usual mannerand purified by being recrystallized from dilute sodium chloridesolution; in

the form of its free acid it corresponds to the structural formulao-sonr on NH:

110 N=N N=NONOQ HOOCIJ 1103s 80311 In chrome printing on cotton theafter-coppered dyeing displays navy blue tints of very good fastness tolight.

EXAMPLE 23 24.9 parts of sulphuric acidmono-(-hydroxy-4-carboxy-Z-aminophenyl) ester (molecular weight 249) arediazotized as described in Example 1 and coupled with 29.4 parts of themonoazo dyestuff obtained by alkaline coupling of diazotized4-aminobenzene-l-sulphonic acid with 1 3-dihydroxybenzene.

Isolation and drying of the resulting disazo dyestulf yields adark-brown powder which dissolves in water with brown coloration and inconcentrated sulphuric acid with violet-brown coloration.

In chrome printing on cotton after-copperingaccom panied by thesplitting of the sulphuric acid ester and by simultaneous formation ofthe ortho:ortho'-dihydroxyazocopper complexyields brown tints of verygood fastness to light.

EXAMPLE 24 24.9 parts of sulphuric acidmono-(5-hydroxy-4-carboxy-Z-aminophenyl) ester (molecular weight 249)are diazotized as described in Example 1 and coupled with 66.7 parts ofthe disazo dyestuif prepared by coupling diazotized4-hydroXy-3-carboXy-3-amino-l: 1-azobenzene-4- sulphonic acid withl-amino-8-naphthol-4:G-disulphonic acid in a weakly acid medium.

The trisazo dyestuif obtained in this manner is purified by beingprecipitated at pH=7 to 8 with sodium chloride, filtered andrecrystallized from dilute sodium chloride solution.

The dyestuflf, dried in vacuo, corresponds in the form of its free acidto the structural formula and forms a greyish black powder whichdissolves in water with blue coloration and in concentrated sulphuricacid with green coloration.

In chrome printing on cotton a dark-green dyeing is obtained which givesa neutral grey tint of very good fastness to light when after-coppered,accompanied by splitting of the sulphuric acid ester and simultaneousformation of the ortho:-ortho'-dihyclroxyazo-copper complex.

What I claim is:

1. An azo dyestuff selected from the group consisting of azo dyestuffsof the formula 1100i; and the copper, cobalt and chromium complexcompounds thereof, wherein X is a member selected from the groupconsisting of H and SO H, and R is the radical of a coupling componentcontaining an OH group in a position vicinal to the carbon atom coupledto the azo bridge of said coupling component being selected from thegroup consisting of coupling components of the acetoacetarylide,pyrazolone, benzene, naphthalene, benzene-azo-benzene,benzene-azmnaphthalene and benzeneazo-b;enzene-azonaphthalene couplingcomponents.

2. An azo dyestuif of the formula 0-SO3H the diazo component HO N=NRN=NOH HO O (B O OH wherein R is the radical of a coupling component of thebenzene series which contains an --OH group in a position vicinal to thecarbon atom coupled to the azo bridge of the diazo component.

3. An azo dyestuff of the formula OSO3H (|)SO:H

free acid the formula I OOOH l H00 OH O-SOaH 5. The aZo-dyestutf whichpossesses in form of the free acid the formula O-BOsH OH Hood OH 6. Theazo-dyestufi which possesses in form of the free acid the formula 0H1O-SOaH ([2 H (30 OH :N-O

ONE OH HO 7. The azo-dyestutf which possesses in form of the free acidthe formula o-s0n t HOQNm H0O 11038 8. The azo-dyestufi which possessesin form free acid the formula OH NH:

SOaH

of the COOH SOaH (References on following page) References Cited in thefile of this patent UNITED STATES PATENTS Schweitzer Sept. 9, 1930 BlackJuly 28, 1936 5 Schulofi Aug. 11, 1936 Maderni July 3, 1956 FOREIGNPATENTS Germany July 1, 1931 44, No. 1, July 1910, pages 1-2. Library.)

(Copy in Scientific

1.AN AZO DYESTUFF SELECTED FROM THE GROUP CONSISTING OF AZO DYESTUFFS OFTHE FORMULAA